The main aim of the European Organization for Research and Treatment of Cancer (EORTC) is to conduct, develop, coordinate and stimulate research in Europe on the experimental and clinical bases of cancer treatment with the final goal being to develop optimal therapeutic strategies in order to improve the standards of cancer treatment in Europe. More than 2000 clinicians/researchers and 283 core medical institutions participate on a voluntary basis in the phase II and large, prospective, randomized, multicenter, phase III clinical trials carried out by 20 different Cooperative Groups. They receive the full logistic and scientific support of the EORTC Data Center, a unique center facility in Europe provides a comprehensive approach to the management of cancer clinical trials. The objectives of the EORTC Data Center are to provide state of the art support to the EORTC Cooperative Groups with respect to data management, computer, statistical and medical expertise at a central and hence economical site. Its goal is to provide and to ensure, from an independent, objective, academic point of view, the highest possible quality of the trial, from its design to the final analysis and publication of the final results. While the EORTC Data Center is concerned with all aspects of trial design, conduct and analysis, Data Center support has recently been given to new areas such as quality assurance, meta-analysis, quality of life, cost effectiveness, and telematics and to new groups dealing with chronotherapy, pathology, and pain and symptom control. New initiatives also involve the development of joint studies with North American Groups and the participation in the elaboration of both Good Clinical Practice guidelines and guidelines from the European Medicine Evaluation Agency on the testing of new anti- cancer drugs. Training and education, quality control and dissemination of information resulting from clinical research are of growing importance from the standpoint of encouraging state of the art treatment for an increasing proportion of cancer patients. The aim of this competing continuation grant application is to request continuation of the support that the EORTC Data Center has received without interruption since 1974 so that it can pursue, reinforce and expand the range of services which it offers to the well established network of investigators participating in the activities of the EORTC Cooperative Groups.